It is a well known fact that AlCl.sub.3 is a most effective antiperspirant salt (Holtze E., Kligman A.: "Mechanism of antiperspirant aluminium salts." J. Soc. Cosmet. Chem. 30, 279 (1979), and Shelley B., Hurley H.J.: "Studies on topical antiperspirant control of axillary hyperhydrosis." Acta Dermatoven. Stockh. 55, 241 (1975)). Most of the comercially available antiperspirant compositions contain AlCl.sub.3 as the active component, e.g. dissolved in a suitable solvent. AlCl.sub.3 exerts its antiperspirant activity by reacting with water to form aluminium hydroxychloride which acts as an astringent and thereby reduces the sweat output of the sweat glands. However, the disadvantage of using AlCl.sub.3 is that the reaction with water to form aluminium hydroxychloride also generates hydrogen chloride or hydrochloric acid as a side product which may cause local skin irritation because of the high acidity; in most clinical studies, 20-50% of the members of the test groups indicated that irritation occurred, and about 10% reported severe irritation (soreness). Also, clothes in contact with the application area may be damaged, and both of these adverse effects can be ascribed to the formation of hydrochloric acid on the skin and in the sweat ducts.
Also, the antiperspirant activity of AlCl.sub.3 is furthermore believed to be partly due to the aluminium hydroxychloride forming a perspiration-blocking "cast" of a polymeric gel precipitate in the sweat ducts. However, the acidity generated in sweat which reacts with AlCl.sub.3 will impair the efficiency of the AlCl.sub.3 -containing composition since AlCl.sub.3 is not capable of forming the gel precipitate when the water with which it reacts has a pH of less than 5; among other things this means that the AlCl.sub.3 composition is not effective when used during sweating.
In the known art, several attempts have been made to prevent the development of acid which causes skin irritation and damaging of clothes. Thus, European Patent No. 70517 describes a two-part kit comprising an AlCl.sub.3 -containing composition and a basic buffer composition, the basic composition being applied subsequent to the AlCl.sub.3 -containing composition but after having allowed the AlCl.sub.3 -containing composition to work for a certain specified period of time. However, as will be self-evident, such a two-stage application sequence is not very practical in actual use since most users would much prefer to have the antiperspirant treatment conducted in a single application.
From the above it is clear that there is a need for an antiperspirant composition which, while still having the advantages conferred by AlCl.sub.3, does not have the consequent disadvantages and which at the same time is simple to use.